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We
thank Dr. Ihab Hosny, Robinson Memorial Hospital, Ravenna, Ohio (USA), for contributing this case. We invite you to contribute a Case of the Week by sending
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Case
of the Week #40

Clinical
history

A 56
year old man had a history of CD20+ (B cell) CLL since 2002. He received
Rituxan (anti-CD20) and Fludarabine and went into remission. In 2005, he
relapsed, and his CLL was now CD20 negative, but CD19+, CD23+ and CD5+. He was
treated with Campath (anti-CD52), and went into remission again. He later developed
dysuria and hematuria. Cystoscopy showed an erythematous bladder. Multiple
biopsies were obtained.

The
diagnosis was confirmed by an immunostain for SV40 T antigen, which was
strongly immunoreactive.

The
polyoma viruses are nonenveloped double-stranded DNA viruses (Stanford
University website). The
polyoma BK virus is widely present in healthy individuals, and may be latent in
the kidney, central nervous system and B cells. Other polyoma viruses are JC,
which causes progressive multifocal leukoencephalopathy, and SV40, which causes
only subclinical infections. The antigens of these polyoma viruses cross-react
serologically and functionally, although they are distinct.

Immunosuppression
may reactivate the latent virus, and cause hemorrhagic cystitis with the
presence of decoy cells, particularly in bone marrow transplant patients. Urine
cytology shows cells with enlarged nuclear and homogenized chromatin due to
viral inclusions (image).
These cells have the same appearance as in our case, and are similarly immunoreactive
for SV40 (image).
Electron microscopy shows 40 nm sized particles (image). A
recent study has found an association of BK virus in immunocompetent patients
with bladder carcinoma, with a 3.4 odds ratio (Diagn
Cytopathol 2006;34:201).